diff --git a/aiter/fused_moe.py b/aiter/fused_moe.py
index 02d6ce0a69..78422707fc 100755
--- a/aiter/fused_moe.py
+++ b/aiter/fused_moe.py
@@ -1707,13 +1707,14 @@ def ck_moe_stage1(
 ):
     token_num = hidden_states.shape[0]
     is_splitk = quant_type is aiter.QuantType.per_1x128 and splitk > 1
-    tmp_out = (
-        torch.zeros(
-            (token_num, topk, w1.shape[1]), dtype=dtypes.fp32, device=out.device
+    if is_splitk:
+        # CK splitK kernel hipMemsetAsync zeros sorted_size * w1.shape[1] floats
+        sorted_size = min(token_num * topk * block_m, sorted_token_ids.shape[0])
+        tmp_out = torch.zeros(
+            (sorted_size, w1.shape[1]), dtype=dtypes.fp32, device=out.device
         )
-        if is_splitk
-        else out
-    )
+    else:
+        tmp_out = out
     aiter.ck_moe_stage1_fwd(
         hidden_states,
         w1,
@@ -1735,10 +1736,11 @@ def ck_moe_stage1(
         out.dtype,
     )
     if is_splitk:
+        valid_out = tmp_out[: token_num * topk, :].contiguous()
         if activation == ActivationType.Silu:
-            aiter.silu_and_mul(out, tmp_out.view(dtypes.fp32))
+            aiter.silu_and_mul(out, valid_out.view(dtypes.fp32))
         else:
-            aiter.gelu_and_mul(out, tmp_out.view(dtypes.fp32))
+            aiter.gelu_and_mul(out, valid_out.view(dtypes.fp32))
     return out